Seven speed dual clutch transmission with four axes of rotation

ABSTRACT

A transmission connectable to an input member and having an output transfer gear, first and second transmission input shaft members, first and second countershaft members, an idler shaft, a plurality of co-planar gear sets, and a plurality of torque transmitting devices. The torque transmitting devices include a plurality of synchronizer assemblies and a dual clutch assembly. The transmission is operable to provide at least one reverse speed ratio and a plurality of forward speed ratios between the transmission input members and the output member.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No.61/177,429, filed on May 12, 2009, which is hereby incorporated in itsentirety herein by reference.

TECHNICAL FIELD

The present disclosure relates to transmissions and more particularly toa compact, dual clutch multiple speed transmission having four axes toestablish seven or more gear speeds.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may or may not constitute priorart.

A typical multiple speed transmission having countershafts and co-planargear sets uses countershaft gears with a different, dedicated gear pairor set to achieve each forward speed ratio. Accordingly, the totalnumber of gears required in this typical design is two times the numberof forward speeds, plus three for reverse. This necessitates a largenumber of required gear pairs, especially in transmissions that have arelatively large number of forward speed ratios.

While current transmissions achieve their intended purpose, the need fornew and improved transmission configurations which exhibit improvedperformance, especially from the standpoints of efficiency,responsiveness and smoothness and improved packaging, primarily reducedsize and weight, is essentially constant. Accordingly, there is a needin the art for a transmission having improved packaging while providingdesirable gear ratios and torque ranges.

SUMMARY

The present invention provides a transmission having first and secondtransmission input members, an output member, first and secondcountershaft members, an idler shaft, a plurality of co-planar gearsets, and a plurality of torque transmitting devices. The torquetransmitting devices include a plurality of synchronizer assemblies anda dual clutch assembly. The transmission is operable to provide at leastone reverse speed ratio and a plurality of forward speed ratios betweenthe transmission input members and the output member.

In one aspect of the present invention, the transmission has atransmission housing and a dual clutch assembly having a clutch housingconnectable to a flywheel of an engine. The clutch housing isrotationally supported within the transmission housing.

In yet another aspect of the present invention, a first, a second, athird, a fourth and a fifth gear set. The first gear set has a firstgear in mesh with a second gear and a third gear, the second gear sethas a first gear in mesh with a second gear and a third gear, the thirdgear set has a first gear in mesh with a second gear and a third gear,the fourth gear set has a first gear in mesh with a second gear and thefifth gear set has a first gear in mesh with a second gear.

In yet another aspect of the present invention, the third gear of thefirst gear set has a first and a second gear teeth portions. The firstgear teeth portion meshes with the second gear of the first gear set andthe second gear teeth portion meshes with a reverse gear.

In yet another aspect of the present invention, a first transmissioninput member has a first end portion and a second end portion rotatablysupported in the transmission housing. Each of the first gear of thethird, fourth and fifth gear sets are rotatably fixed for commonrotation with the first transmission input member.

In yet another aspect of the present invention, a second transmissioninput member has a first end portion and a second end portion rotatablysupported in the transmission housing. Each of the first gear of thefirst and second gear sets are rotatably fixed for common rotation withthe second transmission input member. The second transmission inputmember is concentric with the first transmission input member and atleast partially surrounds the first transmission input member.

In still another aspect of the present invention, a first countershaftis rotatably supported within the transmission housing and spaced apartfrom and parallel with the first and second transmission input members.The reverse gear, the third gear of the second gear set, the third gearof the third gear set and the second gear of the fourth gear set areeach selectively connectable for common rotation with the firstcountershaft.

In still another aspect of the present invention, a second countershaftis rotatably supported within the transmission housing and spaced apartfrom and parallel with the first and second transmission input members.The second gear of the first gear set, the second gear of the secondgear set, the second gear of the third gear set and the second gear ofthe fifth gear set are each selectively connectable for common rotationwith the second countershaft.

In still another aspect of the present invention, an idler shaft isfixedly supported in the transmission housing for rotatably supportingthe third gear of the first gear set. The third gear of the first gearset is free to rotate about the idler shaft.

In still another aspect of the present invention, a first synchronizerassembly selectively connects at least one of the second gear of thefirst gear set and the second gear of the second gear set to the secondcountershaft.

In still another aspect of the present invention, a second synchronizerassembly selectively connects at least one of the reverse gear and thirdgear of the second gear set to the first countershaft.

In still another aspect of the present invention, a third synchronizerassembly selectively connects at least one of the second gear of thethird gear set and the second gear of the fifth gear set to the secondcountershaft.

In still another aspect of the present invention, a fourth synchronizerassembly selectively connects at least one of the third gear of thethird gear set and the second gear of the fourth gear set to the firstcountershaft.

In still another aspect of the present invention, a first countershafttransfer gear is fixed to the first countershaft for common rotationwith the first countershaft and a second countershaft transfer gearfixed to the second countershaft for common rotation with the secondcountershaft. The first and second countershaft transfer gears transfertorque from at least one of the first and second countershafts to anoutput member.

In still another aspect of the present invention, the selectiveengagement of dual clutch assembly interconnects the dual clutch housingwith at least one of the first and the second transmission input membersand the selective engagement of at least one of the synchronizerassemblies establishes at least one of seven forward speed ratiosbetween the at least one of the first and the second transmission inputmembers and the output member.

The above features and advantages and other features and advantages ofthe present invention are readily apparent from the following detaileddescription of the best modes for carrying out the invention when takenin connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a schematic view of an embodiment of a seven speedtransmission, in accordance with the present invention.

DESCRIPTION

Referring to FIG. 1, a multiple speed transmission is generallyindicated by reference number 10. The transmission 10 is connectable toan input member 12 and includes an output member or gear 14. In thepresent embodiment, the input member 12 is a shaft and the output member14 is a gear, however those skilled in the art will appreciate that theinput member 12 may be components other than shafts and the outputmember 14 may be a component, such as a shaft, other than a gear.

The input member 12 is continuously connected with an engine (not shown)or other torque producing machine to provide a driving torque to inputmember 12. The output member or gear 14 rotatably drives a final driveor differential assembly 16. The assembly 16 transfers torque deliveredby output member 14, ultimately, to a pair road wheels (not shown).

The transmission 10 includes a housing 18 that at least partiallyencloses a gearing arrangement 20. The gearing arrangement 20 includesvarious shafts or members, co-planar intermeshing gear sets, a dualclutch assembly, and selectively engageable synchronizers, as will bedescribed herein. For example, the gearing arrangement 20 includes afirst transmission input shaft or member 22, a second transmission inputshaft or member 24, a first countershaft 26, a second countershaft 28and an idler shaft 30. The second transmission input shaft or member 24is a sleeve (hollow) shaft that is concentric with and overlies thefirst transmission input shaft or member 22. The first countershaft 26,the second countershaft 28 and the idler shaft 30 are each spaced apartfrom and parallel with the first and second transmission input shaftmembers 22, 24. The first and second shafts 22, 24 define a first axisof rotation, the first countershaft 26 defines a second axis ofrotation, the second countershaft 28 defines a third axis of rotationand the idler shaft 30 defines a fourth axis of rotation. The positionand location of countershafts 26 and 28 relative to first and secondshafts 22, 24 are interchangeable.

A dual clutch assembly 32 is connected between the input member 12 andthe first and second transmission input shaft members 22, 24. The dualclutch assembly 32 includes a clutch housing 34 connectable for commonrotation with the input member 12. Further, the dual clutch assembly 32has first and second clutch elements or hubs 36 and 38. Clutch elements36 and 38 together with the clutch housing 34 are configured to form afriction clutch, as is known in the art as a dual clutch. Morespecifically, clutch elements 36, 38 and the clutch housing 34 havefriction plates mounted thereon or otherwise coupled thereto thatinteract to form a friction clutch. The clutch element 36 is connectedfor common rotation with the first transmission input shaft or member 22and the clutch element 38 is connected for common rotation with thesecond transmission input shaft or member 24. Thus, selective engagementof clutch element 36 with the clutch housing 34 connects the inputmember 12 for common rotation with the first transmission input shaftmember 22. Selective engagement of clutch element 38 with the clutchhousing 34 connects the input member 12 for common rotation with thesecond transmission input shaft member 24.

The gearing arrangement 20 also includes a plurality of co-planar,meshing gear sets 40, 50, 60, 70 and 80. The present inventioncontemplates that the plurality of co-planar, meshing gear sets 40, 50,60, 70 and 80 may be arranged axially along shafts 22, 24 in an orderother than that which is shown in FIG. 1 and still be within the scopeof the invention. Co-planar gear set 40 includes gear 42, gear 44 andgear 46. Gear 42 is rotatably fixed and connected for common rotationwith the second transmission input shaft member 24. Gear 44 isselectively connectable for common rotation with the second countershaftmember 28 and meshes with gear 42. Gear 46 meshes with gear 42 and isrotatably supported by idler shaft 30 and free to rotate about andindependent of shaft 30. Gear 46 is a stepped gear having a secondarygear portion 47 that is kinematically connected to gear 46 for commonrotation with gear 46. Secondary gear portion 47 may have the same or adifferent gear tooth count or gear pitch relative to other portions ofgear 46, as necessary to implement a desired reverse gear ratio. Itshould be appreciated that gear 42 may be a separate gear structurefixed to the second transmission input shaft member 24 or gearteeth/splines formed on an outer surface of the second transmissioninput shaft member 24 without departing from the scope of the presentinvention. Gear set 40 is disposed proximate a wall 48 of thetransmission housing 18 that is on a front or side of the transmission10 proximate the dual clutch assembly 32.

Co-planar gear set 50 includes gear 52, gear 54 and gear 56. Gear 52 isrotatably fixed and connected for common rotation with the secondtransmission input shaft member 24 and meshes with gear 54 and gear 56.Gear 54 is selectively connectable for common rotation with the secondcountershaft member 28. Gear 56 is selectively connectable for commonrotation with the first countershaft member 26. Gear set 50 ispositioned adjacent gear set 40.

Co-planar gear set 60 includes gear 62, gear 64 and gear 66. Gear 62 isrotatably fixed and connected for common rotation with the firsttransmission input shaft member 22 and meshes with gear 64 and gear 66.Gear 64 is selectively connectable for common rotation with the secondcountershaft member 28. Gear 66 is selectively connectable for commonrotation with the first countershaft member 26. Gear set 60 is disposedadjacent gear set 50.

Co-planar gear set 70 includes gear 72 and gear 74. Gear 72 is rotatablyfixed and connected for common rotation with the first transmissioninput shaft member 22 and meshes with gear 74. Gear 74 is selectivelyconnectable for common rotation with the first countershaft member 26.Gear set 70 is positioned adjacent gear set 60.

Co-planar gear set 80 includes gear 82 and gear 84. Gear 82 is rotatablyfixed and connected for common rotation with the first transmissioninput shaft member 22 and meshes with gear 84. Gear 84 is selectivelyconnectable for common rotation with the second countershaft member 28.Gear set 80 is positioned between gear set 70 and an end wall 88 of thetransmission housing 18.

Reverse gear 90 is selectively connectable for common rotation with thefirst countershaft member 26 and meshes with a secondary gear portion 47of stepped gear 46. Secondary gear portion 47 of gear 46 is fixed forcommon rotation with gear 46. Reverse gear 90 is located between gearset 40 and end wall 48. Reverse gear 90 and secondary gear portion 47may be considered to be a sixth co-planar gear set.

Further, a first countershaft transfer gear 100 is rotatably fixed andconnected for common rotation with the first countershaft member 26. Asecond countershaft transfer gear 110 is rotatably fixed and connectedfor common rotation with the second countershaft member 28. Firstcountershaft transfer gear 100 is configured to mesh with output member14 and the second countershaft transfer gear 110 is configured to meshwith output member 14. However, the first countershaft transfer gear 100and the second countershaft transfer gear 110 do not mesh with eachother. The first countershaft transfer gear 100 is disposed between thereverse gear 90 and end wall 48 of the transmission housing 18. Thesecond countershaft transfer gear 110 is disposed between gear 44 andend wall 48 of the transmission housing 18. The output member 14 isco-planar with first and second countershaft transfer gears 100, 110.

A park gear 112 is provided for placing transmission 10 in a park modethat prevents output member 14 from rotating. Park brake gear 112 isrotatably fixed and connected for common rotation with the secondcountershaft member 28. When the park mode is activated park gear 112 isrotatably fixed preventing second countershaft shaft 28 and transfergear 110 from rotating, which thus prevents output gear 14 fromrotating. Alternatively, the present invention contemplates fixedlydisposing park brake gear 112 on the first countershaft 26 to achievethe park mode function. Moreover, the axial location of park gear 112along the countershafts 26 or 28 may be changed in accordance withavailable packaging space.

The transmission 10 further includes a plurality of selectivelyengageable synchronizer assemblies 150, 152, 154 and 156. Synchronizers150, 152, 154 and 156 are double sided synchronizers and generallyinclude a shift fork (not shown) that is bi-directionally translated byan actuator (not shown) into at least two engaged positions and aneutral or disengaged position. In the present embodiment, synchronizer150 is selectively actuatable to connect gear 44 for common rotationwith the second countershaft member 28 and synchronizer 150 isselectively actuatable to connect gear 54 for common rotation with thesecond countershaft member 28. Synchronizer 152 is selectivelyactuatable to connect for common rotation reverse gear 90 with the firstcountershaft 26 and is selectively actuatable to connect for commonrotation gear 56 with the first countershaft 26. Synchronizer 154 isselectively actuatable to connect for common rotation gear 64 with thesecond countershaft 28 and is selectively actuatable to connect forcommon rotation gear 84 with the second countershaft 28. Synchronizer156 is selectively actuatable to connect for common rotation gear 66with the first countershaft member 26 and is selectively actuatable toconnect for common rotation gear 74 with the first countershaft member26.

The transmission 10 is capable of transmitting torque from the inputshaft 12 to the output gear member 14 in at least seven forward torqueratios and at least one reverse torque ratio. Each of the forward torqueratios and the reverse torque ratio is attained by selective engagementof the dual clutch assembly 32 and one or more of the synchronizerassemblies 150, 152, 154 and 156. Those skilled in the art will readilyunderstand that a different speed ratio is associated with each torqueratio.

It should be appreciated that each individual gear set 40, 50, 60, 70and 80 provides one or more forward and/or reverse gear ratios uponselective engagement of the synchronizer assemblies 150, 152, 154 and156. It should also be appreciated that a particular forward or reversespeed ratio may be achieved by different combinations of synchronizerand associated gear sets without departing from the scope of the presentinvention.

For example, to establish the reverse torque ratio, clutch element 38 isengaged and synchronizer 152 is activated. Clutch element 38 couples theinput member 12 with the second transmission input shaft member 24.Synchronizer 152 connects reverse gear 90 to the first countershaftmember 26. More specifically, input torque from the input shaft 12 istransferred through the dual clutch assembly 32 to the secondtransmission input shaft member 24, through gear 42 to gear 46, throughgear 46 to secondary gear portion 47, through secondary gear portion 47to reverse gear 90, from gear 90 to the first countershaft member 26through synchronizer 152 to first countershaft transfer gear 100 andfrom first countershaft transfer gear 100 to the output member 14.

To establish a first forward torque ratio (i.e. a 1st gear), clutchelement 36 is engaged and synchronizer 154 is activated. Clutch element36 couples the input member 12 with the first transmission input shaftmember 22. Synchronizer 154 couples gear 84 to the second countershaftmember 28. Input torque from the input member 12 is transferred throughthe dual clutch assembly 32 to the first transmission input shaft member22 to gear 82. Gear 82 transfers torque to gear 84 which transfers thetorque to the second countershaft member 28 through synchronizer 154 andto second countershaft transfer gear 110 and then from secondcountershaft transfer gear 110 to the output member 14.

To establish a second forward torque ratio (i.e. a 2nd gear), clutchelement 38 is engaged and synchronizer 150 is activated. Clutch element38 couples the input member 12 to the second transmission input shaftmember 24 which rotates gear 42. Synchronizer 150 couples gear 44 to thesecond countershaft member 28. Accordingly, input torque from the inputmember 12 is transferred through the dual clutch assembly 32 to thesecond transmission input shaft member 24, through gear 42 to gear 44,from gear 44 to synchronizer 150, from synchronizer 150 to the secondcountershaft member 28 and from the second countershaft member 28 to thesecond countershaft transfer gear 110 and the output member 14.

To establish a third forward torque ratio (i.e. a 3rd gear), clutchelement 36 is engaged and synchronizer 156 is activated. Clutch element36 couples the input member 12 to the first transmission input shaftmember 22 which rotates gear 72. Synchronizer 156 couples gear 74 to thefirst countershaft member 26. Thus, input torque from the input member12 is transferred through the dual clutch assembly 32 to the firsttransmission input shaft member 22, through gear 72 to gear 74, throughgear 74 to synchronizer 156, from synchronizer 156 to the firstcountershaft member 26, from the first countershaft member 26 to thefirst countershaft transfer gear 100 and then from first countershafttransfer gear 100 to the output member 14.

To establish a fourth forward torque ratio (i.e. a 4th gear), clutchelement 38 is engaged and synchronizer 152 is activated. Clutch element38 couples the input member 12 to the second transmission input shaftmember 24 which rotates gear 52. Synchronizer 152 couples gear 56 to thefirst countershaft member 26. Thus, input torque from the input member12 is transferred through the dual clutch assembly 32 to the secondtransmission input shaft member 24 to gear 52, then from gear 52 to gear56, from gear 56 to synchronizer 152, from synchronizer 152 to the firstcountershaft member 26, from the first countershaft member 26 to firstcountershaft transfer gear 100 and then from first countershaft transfergear 100 to the output member 14.

To establish a fifth forward torque ratio (i.e. a 5th gear), clutchelement 36 is engaged and synchronizer 156 is activated. Clutch element36 couples the input member 12 to the first transmission input shaftmember 22 which rotates gear 62. Synchronizer 156 couples gear 66 to thefirst countershaft member 26. Input torque from the input member 12 istransferred through the dual clutch assembly 32 to the firsttransmission input shaft member 22, from first transmission input shaftmember 22 to gear 62, from gear 62 to gear 66, from gear 66 to the firstcountershaft member 26 through synchronizer 156, to first countershafttransfer gear 100 and from first countershaft transfer gear 100 to theoutput member 14.

To establish a sixth forward torque ratio (i.e. a 6th gear), clutchelement 38 is engaged and synchronizer 150 is activated. Clutch element38 couples the input member 12 to the second transmission input shaftmember 24 which rotates gear 52. Synchronizer 150 couples gear 54 to thesecond countershaft member 28. Thus, input torque from the input member12 is transferred through the dual clutch assembly 32 to the secondtransmission input shaft member 24 to gear 52, then from gear 52 to gear54, from gear 54 to synchronizer 150, from synchronizer 150 to thesecond countershaft member 28, from the second countershaft member 28 tosecond countershaft transfer gear 110 and then from second countershafttransfer gear 110 to the output member 14.

To establish a seventh forward torque ratio (i.e. a 7th gear), clutchelement 36 is engaged and synchronizer 154 is activated. Clutch element36 couples the input member 12 to the first transmission input shaftmember 22 which rotates gear 62. Synchronizer 154 couples gear 64 to thesecond countershaft member 28. Input torque from the input member 12 istransferred through the dual clutch assembly 32 to the firsttransmission input shaft member 22, from first transmission input shaftmember 22 to gear 62, from gear 62 to gear 64, from gear 64 to thesecond countershaft member 28 through synchronizer 154, to secondcountershaft transfer gear 110 and from second countershaft transfergear 110 to the output member 14.

Again, it should be appreciated that any one of the gear sets of gearsets 40, 50, 60, 70 and 80 may be changed to produce a certain forwardand reverse torque ratio without departing from the scope of the presentinvention.

The present invention contemplates that a variety of torque ratios(i.e., the ratio of torque of the output member 14 to the input member12) and ratio steps are achievable through the selection of tooth countsof the gears of the transmission 10. The present invention has manyadvantages and benefits over the prior art. For example, the utilizationof four synchronizers allows the use of four rails having one fork oneach rail. Moreover, the placement of the park gear 112 on one of thecountershafts 26, 28 improves packaging capability. Thus, a transmissionhaving a more simplified actuation and control system, reduced mass andcost and improved packaging is achieved.

While the best modes for carrying out the invention have been describedin detail, those familiar with the art to which this invention relateswill recognize various alternative designs and embodiments forpracticing the invention within the scope of the appended claims.

1. A transmission comprising: a transmission housing; a dual clutchassembly having a clutch housing connectable to a flywheel of an engine,wherein the clutch housing is rotationally supported within thetransmission housing; a first, second, third, fourth and fifth gear set,wherein the first gear set includes a first gear in mesh with a secondgear and a third gear, the second gear set includes a first gear in meshwith a second gear and a third gear, the third gear set includes a firstgear in mesh with a second gear and a third gear, the fourth gear setincludes a first gear in mesh with a second gear, the fifth gear setincludes a first gear in mesh with a second gear, wherein the third gearof the first gear set has a first and a second gear teeth portions, andwherein the first gear teeth portion meshes with the second gear of thefirst gear set and the second gear teeth portion meshes with a reversegear; a first transmission input member having a first end portion and asecond end portion rotatably supported in the transmission housing, andwherein each of the first gear of the third, fourth and fifth gear setare rotatably fixed for common rotation with the first transmissioninput member; a second transmission input member having a first endportion and a second end portion rotatably supported in the transmissionhousing and, wherein each of the first gear of the first and second gearsets are rotatably fixed for common rotation with the secondtransmission input member and wherein the second transmission inputmember is concentric with the first transmission input member and atleast partially surrounds the first transmission input member; a firstcountershaft rotatably supported within the transmission housing andspaced apart from and parallel with the first and second transmissioninput members, wherein the reverse gear, the third gear of the secondgear set, the third gear of the third gear set and the second gear ofthe fourth gear set are each selectively connectable for common rotationwith the first countershaft; a second countershaft rotatably supportedwithin the transmission housing and spaced apart from and parallel withthe first and second transmission input members, wherein the second gearof the first gear set, the second gear of the second gear set, thesecond gear of the third gear set and the second gear of the fifth gearset are each selectively connectable for common rotation with the secondcountershaft; an idler shaft fixedly supported in the transmissionhousing for rotatably supporting the third gear of the first gear set,wherein the third gear of the first gear set is free to rotate about theidler shaft; four synchronizer assemblies for selectively coupling atleast one of the gears of the first, second, third, fourth and fifthgear sets with at least one of the first countershaft and the secondcountershaft, and wherein the selective engagement of dual clutchassembly interconnects the dual clutch housing with at least one of thefirst and the second transmission input members and the selectiveengagement of at least one of the four synchronizer assembliesestablishes at least one of seven forward speed ratios.
 2. Thetransmission of claim 1 wherein a first of the four synchronizerassemblies selectively connects at least one of the second gear of thefirst gear set and the second gear of the second gear set to the secondcountershaft shaft.
 3. The transmission of claim 2 wherein a second ofthe four synchronizer assemblies selectively connects at least one ofthe reverse gear and third gear of the second gear set to the firstcountershaft shaft.
 4. The transmission of claim 3 wherein a third ofthe four synchronizer assemblies selectively connects at least one ofthe second gear of the third gear set and the second gear of the fifthgear set to the second countershaft shaft.
 5. The transmission of claim4 wherein a fourth of the four synchronizer assemblies selectivelyconnects at least one of the third gear of the third gear set and thesecond gear of the fourth gear set to the first countershaft shaft. 6.The transmission of claim 1 wherein the first gear set is adjacent thedual clutch assembly, the second gear set is adjacent the first gearset, the third gear set is adjacent the second gear set, the fourth gearset is adjacent the third gear set, and the fifth gear set is adjacentthe fourth gear set.
 7. The transmission of claim 6 wherein the dualclutch assembly includes a first clutch and a second clutch, wherein thesecond clutch is configured to selectively connect the input member tothe second interconnecting member and wherein the four synchronizerassemblies includes a first synchronizer assembly for selectivelyconnecting the second gear of the first gear set to the secondcountershaft to establish a second gear ratio.
 8. The transmission ofclaim 6 wherein the dual clutch assembly includes a first clutch and asecond clutch, wherein the second clutch is configured to selectivelyconnect the input member to the second interconnecting member andwherein the four synchronizer assemblies includes a first synchronizerassembly for selectively connecting the second gear of the second gearset to the second countershaft to establish a sixth gear ratio.
 9. Thetransmission of claim 6 wherein the dual clutch assembly includes afirst clutch and a second clutch, wherein the second clutch isconfigured to selectively connect the input member to the secondinterconnecting member and wherein the four synchronizer assembliesincludes a second synchronizer assembly for selectively connecting thereverse gear to the first countershaft to establish a reverse gearratio.
 10. The transmission of claim 6 wherein the dual clutch assemblyincludes a first clutch and a second clutch, wherein the second clutchis configured to selectively connect the input member to the secondinterconnecting member and wherein the four synchronizer assembliesincludes a second synchronizer assembly for selectively connecting thethird gear of the second gear set to the first countershaft to establisha fourth gear ratio.
 11. The transmission of claim 6 wherein the dualclutch assembly includes a first clutch and a second clutch, wherein thefirst clutch is configured to selectively connect the input member tothe first interconnecting member and wherein the four synchronizerassemblies includes a third synchronizer assembly for selectivelyconnecting the second gear of the third gear set to the secondcountershaft to establish a seventh gear ratio.
 12. The transmission ofclaim 6 wherein the dual clutch assembly includes a first clutch and asecond clutch, wherein the first clutch is configured to selectivelyconnect the input member to the first interconnecting member and whereinthe four synchronizer assemblies includes a third synchronizer assemblyfor selectively connecting the second gear of the fifth gear set to thesecond countershaft to establish a first gear ratio.
 13. Thetransmission of claim 6 wherein the dual clutch assembly includes afirst clutch and a second clutch, wherein the first clutch is configuredto selectively connect the input member to the first interconnectingmember and wherein the four synchronizer assemblies includes a fourthsynchronizer assembly for selectively connecting the third gear of thethird gear set to the first countershaft to establish a fifth gearratio.
 14. The transmission of claim 6 wherein the dual clutch assemblyincludes a first clutch and a second clutch, wherein the first clutch isconfigured to selectively connect the input member to the firstinterconnecting member and wherein the four synchronizer assembliesincludes a fourth synchronizer assembly for selectively connecting thesecond gear of the fourth gear set to the first countershaft toestablish a third gear ratio.
 15. The transmission of claim 1 furthercomprising a first countershaft transfer gear fixed to the firstcountershaft for common rotation with the first countershaft and asecond countershaft transfer gear fixed to the second countershaft forcommon rotation with the second countershaft and wherein the first andsecond countershaft transfer gears transfer torque from at least one ofthe first and second countershafts to an output member.
 16. Thetransmission of claim 15 wherein the output member is a gear that mesheswith the each of the first and second countershaft transfer gears. 17.The transmission of claim 15 further comprising a park gear fixed to thesecond countershaft between the second gear of the first gear set andthe second countershaft transfer gear, wherein the park gear isconfigured to prevent rotation of the output gear when the park gear isengaged.
 18. A transmission comprising: a transmission housing; a dualclutch assembly having a clutch housing connectable to a flywheel of anengine, wherein the clutch housing is rotationally supported within thetransmission housing; a first, second, third, fourth and fifth gear set,wherein the first gear set includes a first gear in mesh with a secondgear and a third gear, the second gear set includes a first gear in meshwith a second gear and a third gear, the third gear set includes a firstgear in mesh with a second gear and a third gear, the fourth gear setincludes a first gear in mesh with a second gear, the fifth gear setincludes a first gear in mesh with a second gear, wherein the third gearof the first gear set has a first and a second gear teeth portions, andwherein the first gear teeth portion meshes with the second gear of thefirst gear set and the second gear teeth portion meshes with a reversegear; a first transmission input member having a first end portion and asecond end portion rotatably supported in the transmission housing, andwherein each of the first gear of the third, fourth and fifth gear setare rotatably fixed for common rotation with the first transmissioninput member; a second transmission input member having a first endportion and a second end portion rotatably supported in the transmissionhousing and, wherein each of the first gear of the first and second gearsets are rotatably fixed for common rotation with the secondtransmission input member and wherein the second transmission inputmember is concentric with the first transmission input member and atleast partially surrounds the first transmission input member; a firstcountershaft rotatably supported within the transmission housing andspaced apart from and parallel with the first and second transmissioninput members, wherein the reverse gear, the third gear of the secondgear set, the third gear of the third gear set and the second gear ofthe fourth gear set are each selectively connectable for common rotationwith the first countershaft; a second countershaft rotatably supportedwithin the transmission housing and spaced apart from and parallel withthe first and second transmission input members, wherein the second gearof the first gear set, the second gear of the second gear set, thesecond gear of the third gear set and the second gear of the fifth gearset are each selectively connectable for common rotation with the secondcountershaft; an idler shaft fixedly supported in the transmissionhousing for rotatably supporting the third gear of the first gear set,wherein the third gear of the first gear set is free to rotate about theidler shaft; a first synchronizer assembly selectively connects at leastone of the second gear of the first gear set and the second gear of thesecond gear set to the second countershaft; a second synchronizerassembly selectively connects at least one of the reverse gear and thirdgear of the second gear set to the first countershaft; a thirdsynchronizer assembly selectively connects at least one of the secondgear of the third gear set and the second gear of the fifth gear set tothe second countershaft; a fourth synchronizer assembly selectivelyconnects at least one of the third gear of the third gear set and thesecond gear of the fourth gear set to the first countershaft; a firstcountershaft transfer gear fixed to the first countershaft for commonrotation with the first countershaft and a second countershaft transfergear fixed to the second countershaft for common rotation with thesecond countershaft and wherein the first and second countershafttransfer gears transfer torque from at least one of the first and secondcountershafts to an output member, and wherein the selective engagementof dual clutch assembly interconnects the dual clutch housing with atleast one of the first and the second transmission input members and theselective engagement of at least one of the synchronizer assembliesestablishes at least one of seven forward speed ratios between the atleast one of the first and the second transmission input members and theoutput member.